Measurement method for detecting and quantifying combustor dynamic pressures

Abstract

A method of detecting combustor dynamic pressures in combustors of a gas turbine combustor includes the steps of: a) mounting at least one accelerometer ( 24 ) on a combustor casing; b) establishing a baseline vibration signature for the casing when combustion dynamics are minimal; and c) measuring subsequent vibration signatures and comparing those signatures to the baseline signature.

What is claimed is:  
     
       1. A method of detecting combustor dynamic pressures in combustors of a gas turbine combustor wherein the combustors are enclosed within an external casing, and each combustor is partially defined by a combustion liner that is partially surrounded by a flow sleeve, the method comprising: 
       a) mounting at least one accelerometer on an external surface of the external combustor casing;  
       b) establishing a baseline vibration signature for the casing when the gas turbine combustor is in a diffusion flame mode when combustion dynamics are minimal; and  
       c) measuring subsequent vibration signatures for the external casing when the gas turbine combustor is under load and comparing those signatures to said baseline signature to identify anomalies in said subsequent vibration signatures and thus detect onset of excessive combustor dynamic pressures.  
     
     
       2. The method of  claim 1  wherein said vibration signatures comprise a plot of vibration amplitude vs. frequency. 
     
     
       3. The method of  claim 1  wherein at least one accelerometer is mounted on each combustor casing of the gas turbine. 
     
     
       4. The method of  claim 1  including the step of: 
       d) displaying the baseline and subsequent vibration signatures on a screen.  
     
     
       5. The method of  claim 4  wherein steps a), b), c) and d) are carried out for each combustor in the gas turbine. 
     
     
       6. The method of  claim 1  wherein step a) is carried out by securing a block on the combustor casing and attaching the accelerometer to the block. 
     
     
       7. The method of  claim 1  wherein an accelerometer is mounted on each combustor of the gas turbine, and wherein each accelerometer is oriented to measure vibrations in a radially outward direction. 
     
     
       8. A method of detecting combustor dynamic pressures in combustors of a gas turbine combustor comprising: 
       a) mounting at least one accelerometer on a combustor casing;  
       b) establishing a baseline vibration signature for the casing when combustion dynamics are minimal; and  
       c) measuring subsequent vibration signatures and comparing those signatures to said baseline signature;  
       wherein step a) is carried out by securing a block on the combustor casing and attaching the accelerometer to the block; and wherein the accelerometer is oriented to measure vibrations in a radially outward direction.  
     
     
       9. A method of detecting combustor dynamic pressures in combustors of a gas turbine combustor comprising: 
       a) mounting at least one accelerometer on a combustor casing;  
       b) establishing a baseline vibration signature for the casing when combustion dynamics are minimal; and  
       c) measuring subsequent vibration signatures and comparing those signatures to said baseline signature;  
       wherein an accelerometer is mounted on each combustor of the gas turbine, and wherein each accelerometer is oriented to measure vibrations in a radially outward direction; and further wherein step b) is carried out when the gas turbine combustor is in a diffusion flame mode, and wherein step c) is carried out when the gas turbine combustor is under load.